MONDAY, April 7, 2014 (HealthDay News) -- Contrary to a recent report with encouraging figures on childhood obesity in the United States, a new study presents a more sobering picture of the nation's pediatric weight problem.

Severe obesity, which sets kids up for a lifetime of health problems, has increased over the past 14 years, North Carolina researchers found. They used the same data that researchers from the U.S. Centers for Disease Control and Prevention mined for their encouraging report in February.

"We found that the number of extremely obese kids seems to be increasing," said lead researcher Asheley Cockrell Skinner, an assistant professor of pediatrics at the University of North Carolina. "This is particularly true for school-age girls and teenage boys."

Severely obese children are the ones most likely to have type 2 diabetes as teens and other problems such as heart disease later in life. They are also the children who will require millions of dollars in health care costs, she added.

Moreover, all obese children are likely to be obese adults, Skinner said.

Categories of obesity are based on a child's height and weight in relation to their peers. A 10-year-old boy who is 4 feet, 6 inches tall and weighs 95 pounds is considered obese, according to Dr. David Katz, director of the Yale University Prevention Research Center. At 130 pounds, that boy would be severely obese.

For the new report, published online April 7 in the journal JAMA Pediatrics, Skinner and a colleague used the same National Health and Nutrition Examination Survey data as the CDC researchers, but extended their research from 1999 to 2012.

In the CDC study, published Feb. 26 in the Journal of the American Medical Association, researchers found a significant decrease in obesity among preschoolers -- from 14 percent in 2003-04 to about 8 percent in 2011-12.

That CDC study also found that obesity rates had stabilized among children overall, and some specialists hailed the report as an indication of a turnaround.

But their excitement may have been premature, Skinner said. She added: "When extending the data out to 14 years, we see there isn't really a decline. We need to be cautious about reports that say obesity is declining and assume things are better."

Katz called the new findings alarming.

"This paper will come as a sobering reality check for any who believed the recent headlines about childhood obesity rates plummeting," he said.

Severe obesity in children is rising, he said, adding that this is a critical piece of information.

"Severe obesity is much more likely to induce serious chronic disease and steal years from life," Katz said. "It calls out for clinical interventions, up to and including weight-loss surgery."

Also, a cultural sea change is needed, Katz said. "We cannot deny kids daily physical activity and peddle junk foods to them and fail to reap what we are sowing," he said.

Skinner agreed. "Every kid in this country deserves access to healthy food and chances to be active," she said.

For the new study, Skinner's team examined data on nearly 26,700 children ages 2 to 19 years old. For the years 2011-12, they found 32 percent of America's children were overweight and 17 percent were obese. Among obese kids, 8 percent were severely obese, the researchers said.

When specific categories of obesity were examined, more bad news emerged. Among girls, the researchers found obesity rates jumped from 14.5 percent in 1999-2000 to 17.4 percent by 2011-12. And severe obesity among girls climbed from 0.9 percent in 1999-2000 to 2.3 percent by 2011-12.

In boys, obesity rose from 14.6 percent in 1999-2000 to 17.2 percent by 2011-12, while severe obesity grew from 1 percent to 2 percent.

More research is needed to determine which public health programs, if any, are helpful in preventing obesity, the study authors said.

Whether public health campaigns alone will turn around rates of severe obesity is questionable, the researchers said.

"Unfortunately, the high prevalence and upward trend of more severe forms of obesity will likely require more intensive interventions than can be done through widespread public health efforts," the study said.